[GRASS-dev] vlib api: is area an isle?

Martin Landa landa.martin at gmail.com
Sat Mar 23 11:01:45 PDT 2013


I am trying to find a way how to determine if an area forms an isle
using vlib API? Eg.

$ v.buffer in=roadsmajor out=rb dist=1000


17 areas (1 area with category + 16 areas (without categories) forms isles)
17 isles (one "universal isle" + 16 "holes" in area)

Is there any way how to determine from topology that given area forms
an isle. Such area has no category, but it's a weak precondition. We
can have areas with no category (no centroid defined for such area)
which do not form isles ("hole in polygon" from simple feature

I would like to go through all areas and skip the areas which form isles.

for (area = 1; area <= nareas; area) {
     if (Vect_is_area_isle(Map, area)

Thanks for any pointers (I just cannot find it), Martin

Martin Landa <landa.martin gmail.com> * http://geo.fsv.cvut.cz/~landa

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